Radiation therapy is routinely used to treat invasive medical diseases such as cancer for instance. The principle behind beam therapy consists in an x-ray beam killing off cancerous cells. If the beam is directed at a cancer tissue or another abnormal area, the cells are destroyed. It is nevertheless unavoidable that the beam also damages healthy surrounding tissue. If the radiation is therefore not adequately restricted, the side effects for a patient can be serious.
A restriction of this type is usually achieved by collimating the beam, so that it only expands across the minimal required region so as to capture the whole cancer, but only a minimal region of the healthy surrounding tissue. Multileaf collimators are known for this purpose, with which leaves are inserted and/or removed into/from the beam so as to predeterminably change the shape of the developing beam.
The disadvantage of multileaf collimators is that the beam formation is restricted and undercut or hollow openings cannot be realized. Furthermore, the continuous beam inside the beam cannot be influenced, in other words a dose profile can only be influenced at the beam edge. Known types are also either very slow in adjusting the leaves or only allow two positions per leaf.
An improvement is achieved by the subject matter of DE 102 21 634 B4. The apparatus for spatial modulation of an x-ray beam bundle includes a plurality of flat attenuating elements for x-ray radiation, which are arranged on a support in the manner of a matrix and can be piezoelectrically pivoted or tilted independently of one another between at least two positions. For beam therapy, there is however often the desire to achieve a higher resolution of the matrix and to increase the modulation speed.